In connection with statics calculations for escalators, consideration must be given to vertical framework oscillations which can be excited by chain engagement (resonant oscillations). When safety factors are applied, due to the sensitivity of the framework oscillation system relatively large forbidden regions result, particularly in the case of moving walkways with equal bay divisions. In the case of escalators with unequal bay divisions, these regions may be even larger due to the nature of safety factor computation and application. For these reasons only relatively small bay widths are often available.